The Messerschmitt Me 163 Komet, designed by Alexander Lippisch, was a German rocket-poweredfighter aircraft. It is the only rocket-powered fighter aircraft ever to have been operational and the first piloted aircraft of any type to exceed 1000 km/h (621 mph) in level flight. Its design was revolutionary and its performance unprecedented. German test pilot Heini Dittmar in early July 1944 reached 1,130 km/h (700 mph), an unofficial flight airspeed record unmatched by turbojet-powered aircraft for almost a decade. Over 300 aircraft were built, but the Komet proved ineffective in its dedicated role as an interceptor aircraft and was responsible for the destruction of only about nine to eighteen Allied aircraft against ten losses.[2][3] Aside from combat losses many pilots were killed during testing and training.[4]

Development

An early Walter HWK 109-509A-1 rocket motor, believed to be one of the best preserved in existence and possibly used for instructional purposes.[5] The cockpit is a mockup. (Shuttleworth Collection, UK) The main oxidizer tank between the cockpit's rear wall and the front of the engine[6]was omitted, making the mockup shorter than the complete fuselage.

Work on the design started[when?]under the aegis of the Deutsche Forschungsanstalt für Segelflug (DFS)—the German Institute for the Study of sailplane flight. Their first design was a conversion of the earlier Lippisch Delta IVknown as the DFS 39 and used purely as a glider testbed of the airframe. A larger follow-on version with a small propeller engine started as the DFS 194. This version used wingtip-mounted rudders, which Lippisch felt would cause problems at high speed. Lippisch changed the system of vertical stabilization for the DFS 194's airframe from the earlier DFS 39's wingtip rudders, to a conventional vertical stabilizer at the rear of the aircraft. The design included a number of features from its origins as a glider, notably a skid used for landings, which could be retracted into the aircraft's keel in flight. For takeoff, a pair of wheels, each mounted onto the ends of a specially designed cross-axle, were needed due to the weight of the fuel, but the wheels, forming a takeoff "dolly" under the landing skid, were released shortly after takeoff.[7]

The designers planned to use the forthcoming Walter R-1-203cold engine of 400 kg (880 lb) thrust, which like the self-contained Walter HWK 109-500StarthilfeRATO booster rocket unit, used a monopropellant consisting of stabilized HTP known by the name T-Stoff. Heinkel had also been working with Hellmuth Walter on his rocket engines, mounting them in the He 112R's tail for testing - this was done in competition with Wernher von Braun's bi-propellant, alcohol/LOX-fed rocket motors, also with the He 112 as a test airframe - and with the Walter catalyzed HTP propulsion format for the first purpose-designed, liquid-fueled rocket aircraft, the He 176. Heinkel had also been selected to produce the fuselage for the DFS 194 when it entered production,[when?] as it was felt that the highly volatile monopropellant "fuel's" reactivity with organic matter would be too dangerous in a wooden fuselage structure. Work continued under the code name Projekt X.[8]

The division of work between DFS and Heinkel led to problems,[when?] notably that DFS seemed incapable of building even a prototype fuselage. Lippisch eventually asked to leave DFS and join Messerschmitt instead. On 2 January 1939, he moved with his team and the partly completed DFS 194 to the Messerschmitt works at Augsburg. The delays caused by this move allowed the engine development to "catch up". Once at Messerschmitt, the team decided to abandon the propeller-powered version and move directly to rocket-power. The airframe was completed in Augsburg and in early 1940 was shipped to receive its engine at Peenemünde-West, one of the quartet of Erprobungsstelle-designated military aviation test facilities of the Reich. Although the engine proved to be extremely unreliable, the aircraft had excellent performance, reaching a speed of 550 km/h (340 mph) in one test.[9]

In the Me 163B and -C subtypes, a ram-air turbine on the extreme nose of the fuselage, and the backup lead-acid battery inside the fuselage that it charged, provided the electrical power for the radio, the Revi16B, -C, or -D reflector gunsight, the direction finder, the compass, the firing circuits of the cannon, and some of the lighting in the cockpit instrumentation.

There was an onboard lead/acid battery, but its capacity was limited, as was its endurance, no more than 10 minutes, hence the fitted generator.

The airspeed indicator averaged readings from two sources: the pitot tube on the leading edge of the port wing, and a small pitot inlet in the nose, just above the top edge of the underskid channel. There was a further tapping-off of pressure-ducted air from the pitot tube which also provided the rate of climb indicator with its source.

Me 163A

The Me 163A V4 prototype, in 1941

In early 1941 production of a prototype series, known as the Me 163, began. Secrecy was such that the RLM's "GL/C" airframe number, 8-163, was actually that of the earlier, pre-July 1938 Messerschmitt Bf 163. It was thought that intelligence services would conclude any reference to the number "163" would be for that earlier design. In May 1941 the Me 163A V4 was shipped to Peenemünde to receive the HWK RII-203 engine. By 2 October 1941, the Me 163A V4, bearing the radio call sign letters, or Stammkennzeichen, "KE+SW", set a new world speed record of 1,004.5 km/h (624.2 mph), piloted by Heini Dittmar, with no apparent damage to the aircraft during the attempt.[10][11]Some postwar aviation history publications stated that the Me 163A V3 was thought to have set the record.[12]

The 1,004 km/h record figure would not be officially approached until the postwar period by the new British and U.S.jet fighters. It was not surpassed (except by the later Me 163B V18 in 1944, but seriously damaged by the attempt) until the American Douglas Skystreak turbojet-powered research aircraft did so on 20 August 1947 with no damage. Five prototype Me 163A V-series aircraft were built, adding to the original DFS 194 (V1), followed by eight pre-production examples designated as "Me 163 A-0".[13]

Landing gear and ground handling procedures

During testing, the jettisonable main landing gear arrangement, of a differing design to that used on the later B-series production aircraft, was a serious problem. The A-series "dolly" landing gear caused many aircraft to be damaged on takeoff when the wheels rebounded and crashed into the aircraft due to the sizable springs and shock absorbers on the A-series "dolly" devices which possessed well-sprung independent suspension systems for each main wheel,[14] not used on the much simpler, crossbeam-axled B-series aircraft dollies. The landing skid on the B-series Komet design possessed a oleo-pneumatic strut for the extendable skid,[15] which had to remain extended after attachment of the dolly to absorb ground-running impacts during the takeoff run and for shock absorption on landing.[16] If the hydraulic cylinder was malfunctioning—or if the pilot simply forgot to release the hydraulic pressure on the skid before landing, after extending it for touchdown to absorb the force of the landing itself—the resulting unbuffered impact of a hard touchdown on the skid could cause back injuries to the pilot when landing.

Once on the ground, the aircraft had to be retrieved by a Scheuch-Schlepper, a converted small agricultural vehicle,[17] originally based on the concept of the two-wheel tractor, carrying a detachable third swiveling wheel at the extreme rear of its design for stability in normal use—this swiveling third wheel was replaced with a pivoting, special retrieval trailer that rolled on a pair of short, triple-wheeled continuous track setups (one per side) for military service wherever the Komet was based. This retrieval trailer usually possessed twin trailing lifting arms, that lifted the stationary aircraft off the ground from under each wing whenever it was not already on its twin-wheel "dolly" main gear, as when the aircraft had landed on its ventral skid and tailwheel after a mission.[18] Another form of trailer, known also to have been trialled with the later B-series examples, was tried during the Komet's test phase, which used a pair of sausage-shaped air bags in place of the lifting arms and could also be towed by the Scheuch-Schlepper tractor, inflating the air bags to lift the aircraft.[19][20] The three-wheeled Scheuch-Schlepper tractor used for the task was originally meant for farm use, but such a vehicle with a specialized trailer was required as the Komet was unpowered after exhausting its rocket propellants, and lacked main wheels after landing, from the jettisoning of its "dolly" main gear at takeoff.[21] The slightly larger Sd Kfz 2Kettenkrad half-track motorcycle, known to be used with the Me 262 jet fighter for ground handling needs, and documented as also being used with the Arado Ar 234B jet recon-bomber,[22] was not known to have ever been used for ground handling operations with the Komet at any time.

During flight testing, the superior gliding capability of the Komet proved detrimental to safe landing. As the now un-powered aircraft completed its final descent, it could rise back into the air with the slightest updraft. Since the approach was unpowered, there was no opportunity to make another landing pass. For production models, a set of landing flaps allowed somewhat more controlled landings. This issue remained a problem throughout the program. Nevertheless, the overall performance was tremendous, and plans were made to put Me 163 squadrons all over Germany in 40-kilometre rings (25 mi) around any potential target. Development of an operational version was given the highest priority.[citation needed]